The Aniak district (fig. 12) is the area drained by the Kusko¬kwim River and its tributaries above Bethel as far as (and includ¬ing) the Stony River.
The principal center of mining in the district was near Nyac, where placer deposits on the Tuluksak River (6—8, fig. 12) and Bear (9, 10, fig. 12) and California (8, fig. 12) Creeks and their tributaries were mined from 1909 until the end of the 1964 sea¬son when the last of three dredges was shut down. The source of most of the gold was low-grade gold- and sulfide-bearing quartz veins in contact zones between Cretaceous volcanic rocks and Tertiary granitic plutons and in the plutons themselves. Cinna¬bar, probably originally assiciated with extensively altered dia¬basic dikes or sills, constituted a large part of the concentrates of a dredge operating on Bear Creek near the mouth of Bonanza Creek (10, fig. 12). A little platinum was recovered by some of the dredges in the area, but the amount is unknown. Less rich and less extensive placer deposits similar to those near Nyac were prospected or mined on Granite (5, fig. 12), Ophir (12, fig. 12), and other creeks.
Successful mining has been carried on for many years on Mar¬vel Creek (15, fig. 12) and, to a lesser extent, on other tributaries of the Salmon River. The gold in the placers was derived from contact zones between granitic plutons and clastic Cretaceous rocks. Unlike the area near Nyac, sulfide minerals have not been reported in concentrates or in quartz veinlets in contact zones. Until 1966, when a small dredge was brought to Marvel Creek from Nyac, all operations were by nonfioat, hydraulic, and hand methods. Farther south, on Canyon Creek (1, fig. 12), one of the headwaters of the Kwethluk River, there has also been mining in practically every year since gold was discovered there in 1913. Canyon Creek crosses a contact zone, the probable source of the gold in the placers, between a quartz porphyry body and Paleo¬ zoic or Mesozoic clastic rocks. Hoare and Coonrad (1959a) found evidence of prospecting or small-scale mining on Columbia (2, fig 12) and Rocky (3, fig. 12) Creeks, but no reports of success¬ful mining on these or other streams in the basin of the Kisaralik River have been published. A report of cassiterite from the Rigiagalik (Martin, 1919, p. 20) River, another name for the Kisara¬uk was probably false.
After the Nyac area, the most productive part of the Aniak district was the basin of Crooked Creek (21, fig. 12), where benches about 1 mile wide lying east and southeast of and parallel to the main stream and its principal tributary, Donlin Creek (23, 24 fig. 12), were mined from about 1910 until at least as recently as 1956. The gold was derived from small quartz fracture fillings in Cretaceous graywacke and shale near small silicified porphyritic albite rhyolite intrusive bodies. The richest placers were on Snow and other left-limit gulches (22, fig. 12) in which gold from the benches had been further concentrated. In addition to gold, con¬centrates contained magnetite, garnet, scheelite, cassiterite, pyrite, cinnabar, and stibnite. Only the gold was saved. Julian Creek (26, fig. 12), a tributary of the George River, drains a source area similar to that of the Crooked Creek-Donlin Creek placers and was mined sporadically from about 1911 to 1939. Concentrate samples contained gold, pyrite, some- cinnabar, and traces of monazite. Other streams, such as Murray Gulch (20, fig. 12) near Napamute and small tributaries of the Kuskokwim River between Crooked Creek and Sleetmute (25, 27—29, fig. 12), drain geologically similar areas and were sites of prospecting or mining before World War II, but only Murray Gulch and New York Creek (20, fig. 12) have ever been listed as producing streams.
In the upper Holitna River basin, gold has been recovered from Taylor (31, fig. 12) and Fortyseven (19, fig. 12) Creeks. Cassi¬terite, cinnabar, and pyrite accompany the gold in Taylor Creek; all were probably derived from mineralized zones in Cretaceous clastic rocks in the Taylor Mountains, where they were altered to hornfels around a quartz monzonite stock, or from mineraliza¬tion associated with small albite rhyolite intrusive bodies in the nearby Little Taylor Mountains. Somewhat more than 2,000 ounces of gold is said to have been recovered from Taylor Creek. Fortyseven Creek drains a ridge on which there is a scheelite¬and gold-bearing lode in a silicified shear zOne in graywacke and shale. Both gold and scheelite have been recovered from placer deposits below the lode. Scheelite has also been reported in an indefinitely described area west of the Horn Mountains about 15 miles north of Napamute and wolframite has been reported in float on a ridge west of Stevens Creek (30, fig. 12).
Placer cinnabar was mined from Cinnabar Creek (18, fig. 12), immediately downstream from the Cinnabar Creek lode mine, described by Sainsbury and MacKevett (1965, p. 38—40). Although the placer production probably was small, it is of particular inter¬est because it is one of the few examples of successful primary